Powertrain, generic · Computer and auxiliary outputs

P0601 Internal Control Module Memory Checksum Error

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The module continuously calculates a checksum over its program and calibration memory (flash) and compares it with the stored value; on newer units the flash error correction also reports bit errors it cannot repair. A mismatch means the stored software is corrupted. GM sets P0601 in the engine module after one failed pass (or five once the first pass is complete) and turns on the lamp in the first trip; in body modules after two trips. Ford reports the same check as P0605, while GM, VW and Mazda use P0601. Typical causes are an interrupted reflash and manufacturer software errors – VW (2.0 TFSI) and Mazda (MX-5 2013) fixed it by reprogramming. The code alone does not say which module set it – the scan tool shows whether it is the engine, transmission, brake or body module.

Likely causes

Interrupted or faulty reprogramming
Faulty module software (update available)
Defective flash memory in the module
Low voltage, voltage dips or a poor ground or supply at the module

Symptoms

  • Check engine light on
  • Often no change in driving
  • Possibly no start or limp mode if the software is badly damaged
  • Transmission limp mode if the transmission module is affected

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

  1. Check for available software updates
  2. Reprogram the module
  3. Replace module if reprogramming fails

Parts involved

engine control modulecontrol module power supplycontrol module ground

Related codes

P0602P0603P0604P0605P062FP0606

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.